From DE 197 55 513 C2, an expansion connector for successive busbars of a contact line is known. The expansion connector can be plugged into longitudinal cavities of adjacent busbars and automatically produces the electrical connection between the busbars. For this purpose, it has a plastic holder which has a cross bar at the height of the longitudinal cavities of the two busbars, from which two metal bars go out, on both sides and in the longitudinal direction of the busbars; in a direction vertical to the longitudinal direction and the cross bar, these metal bars are acted on elastically so they are kept apart. The metal bars mesh into the longitudinal cavities and are pressed elastically against the inside surface of the metal profile of the busbars. There, the elastic action of the metal bars should ensure that an electrical connection is guaranteed to be secure in all conceivable relative positions of the busbars and the plastic holder. The design of the expansion connector, however, is complex, since, there, the coil springs, which force apart the metal bars, must be inserted into the boreholes of the cross bar.
If the spring force slackens over the course of time, there is also the risk of an undesired loosening of the connected busbars. Furthermore, for the secure fastening of the plastic holder on the busbars, molded pins must be provided on the plastic holder; they mesh into corresponding boreholes of the expansion connector. This is disadvantageous since the plastic pins can break off. In addition, during the installation, an exact centering of the pins on the boreholes must be carried out. These structures increase the construction cost for the production of the expansion connector and complicate the installation of the expansion connector in situ.
FR 2 889 773 A1 discloses a connecting element of a contact line with two claws, which embrace the lateral walls of the contact line busbars and press them against a stop element, so as to make possible both a mechanical and also an electrically secure connection. For the fixing, the claws are screwed with one another in an expensive and time-consuming process. In addition, holes into the lateral walls of the contact lines and corresponding pins on the connecting element are provided there, so as to prevent a displacement of the connecting element in the longitudinal direction. Since the claws are fixed via screw connections which can be loosened, in turn, a permanent deformation of the bent lateral flanks there is not desired and is prevented by, among other things, a stop element that is situated between the lateral flanks.
DE 295 09 987 U1 discloses an assembly kit of plug connectors for connecting at least two single- or multiphase busbars in the low-voltage range for the installation of lights in the low-voltage range. The plug connector is solidly constructed, so that it completely closes the cavities into the busbars which are to be connected. Thus, it cannot be inserted in contact lines, since in their cavities, the sliding contacts must be able to engage freely and slide through.
DE 196 41 090 C2 discloses a connector for busbars, wherein the connector is an elbow that consists of a hinge in at least two parts that are connected with one another by a hinged axle in such a way that they can rotate. Coupling parts are placed on the elbow parts; they are plugged into cavities on the ends of the busbars that are to be connected with one another. The elbow does not have a continuous cavity, so that the connector cannot be used with contact lines, since the sliding contacts cannot slide freely through the cavities of the busbars.